A storage area network (SAN) is a dedicated network that provides access to consolidated, block level data storage. SANs are primarily used to make storage devices, such as disk arrays, tape libraries, and optical drives, accessible to servers so that the devices appear like they are locally attached to the operating system. A SAN typically has its own network of storage devices that are generally not accessible through the local area network by other devices. The cost and complexity of SANs has dropped to levels allowing wider adoption across both enterprise and small to medium sized business environments.
Network-attached storage (NAS) is file-level computer data storage connected to a computer network providing data access to a heterogeneous group of clients. NAS not only operates as a file server, but is specialized for this task either by its hardware, software, or configuration of those elements. NAS is often manufactured as a computer appliance—a specialized computer built from the ground up for storing and serving files—rather than simply a general purpose computer being used for the role.
NAS systems are networked appliances which contain one or more hard drives, often arranged into logical, redundant storage containers or RAID arrays. Network-attached storage removes the responsibility of file serving from other servers on the network. NAS devices are gaining popularity, as a convenient method of sharing files among multiple computers.
Unfortunately, the cost and complexity of SAN and NAS systems increases with scale. Therefore, it is difficult and expensive to deliver storage systems in the 100+ petabyte (PB) range. Indeed, existing solutions call for expensive hardware and dedicated field service engineers.